On 14 Apr 2021, at 11:15 pm, Robert Kern <robert.k...@gmail.com> wrote: > > On Wed, Apr 14, 2021 at 4:37 PM Joachim Wuttke <j.wut...@fz-juelich.de> wrote: > Regarding numpy, I'd propose a bolder measure: > To let savetxt(fname, X, ...) store exactly the same information in > compressed and uncompressed files, always invoke gzip with mtime = 0. > > I agree. > I would caution though that relying on the checksum or similar of the compressed data still does not seem a very robust check of the data itself - the compressed file would still definitely change with any change in compression level, and quite possibly with changes in the linked compression library (perhaps even a simple version update).
Shouldn’t you better verify the data buffers themselves? Outside of Python, the lzma utility xzcmp for example allows binary comparison of the content of compressed files independently from the timestamp or even compression method, and it handles gzip and bzip2 files as well. > I would like to follow up with a pull request, but I am unable to > find out how numpy.savetxt is invoking gzip. > > `savetxt` uses the abstractions in this module to invoke gzip when the > filename calls for it: > > https://github.com/numpy/numpy/blob/main/numpy/lib/_datasource.py#L115 > One obstacle would be that this is setting gzip.open as _file_opener, which does not have the mtime option; getting this replaced with gzip.GzipFile to work in text mode would require to somehow replicate gzip.open’s io.TextIOWrapper wrapping of GzipFile. Cheers, Derek _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@python.org https://mail.python.org/mailman/listinfo/numpy-discussion
